Own-Roots versus
Grafts:
There is an endless debate about "own-root" versus
"grafted/budded"
plants. Depending on which book you read, or who you talk to.
Own-roots plants are plants that are not grafted whose
rootstock
(the
roots system) is the same type as the top of the plant. They
are one variety from the top flower bud down to the last root. While
a grafted plant, is a plant where the desired plant is grafted or
budded onto a rootstock of a different type. The point where the
desired variety and the rootstock meet is called the
graft union (or
bud union).
Don't confuse own-root plants with
bare-root plants, the terms refer
to different things. Plants are usually sold either bare-root (no
soil around the roots) or
potted in containers. Bare-root plants can
be either own-root or grafted.
Grafting a small piece of
stem or
bud from the desired plant onto a vigorous
other variety rootstock is a fast way to produce the desired
variety. There are some good reasons to graft plants for some
varieties. A vigorous rootstock can make a weaker variety grow well.
Own root plants are usually smaller than grafted one in the
beginning while grafts grow very rapidly. Some rare
cacti for example are
very difficult or extremely slow to grow from their own roots and
only a few expert cactus enthusiasts attempt to cultivate them on
their own root.. Many plant are sold as grafted plants, since it is
more economical than selling own-root, but most of them are vigorous
enough to grow well without grafting.
Unfortunately, there are some disadvantages to grafting, too. The
graft will potentially be a weak spot for the
lifetime of the plant,
own-root plants have (usually) a much longer
life than grafted ones.
After some years, some grafted plants tends to form a knot at the
graft union and the plant loses its
vigour and must cease to
grow.
This is not a problem for own-root plants, since they lack the knobby graft union of grafted ones. Own root plants are also much
truer to type than grafted ones.

Sometimes shoots will emerge from the rootstock. If the plant is
grafted this shoot or
sucker will be the same
type of the
rootstock, not the desired plant. When this happens with own-root
plants, the shoot will be of the desired variety. With own-root
plant you never have to bother with removing unwanted shoots of the
rootstock variety. De-suckering is very important for grafted plants
as without it the vigorous rootstock can take over and replace the
original plant